The present invention relates to a beam for supporting a sliding carriage as it moves relative to a medium to be scanned, for example in hardcopy apparatus such as a printer.
In prior art printers, the beam for supporting the printhead-carrying carriage is a structural element which is required to provide rigidity for the printer. For this reason, such beams have a substantially rectangular cross-section which, in particular for sheet metal beams, provides the required degree of stiffness.
A problem with the rectangular cross-section is that it prevents various components being arranged relatively closely together which it would be desirable to achieve. In a printer, the relevant components are the slider rod, the printhead, the drive belt and/or the encoder device.
The present invention seeks to overcome or reduce the above problem.
According to the present invention, there is provided a scanning device comprising a structural beam supporting:
a) a guide member,
b) a scanning head member moveably mounted on said guide member and moving parallel to a scanning plane (B), and further supporting:
c) a drive mechanism for moving the scanning head member, and/or
d) an encoder device for determining the position of the scanning head member relative to the rest of the device,
the beam having a plurality of faces including a first face, which is substantially parallel to the scanning plane (B), and an adjoining second face facing the guide member,
in which the second face includes at least a first portion, which is closest to the guide member, and a second portion, which is set back from the first portion.
An advantage of the above device is that the drive mechanism and/or encoder device can be located in front of the second portion. This leads to an arrangement in which the various components mentioned can all be located close to the guide member. In particular it also provides a vertically compact arrangement. When the scanning device is a printer, it will be appreciated that the scanning plane corresponds to the plane in which the media advances.
In a preferred embodiment, the entire second face is inclined at an angle of 50xc2x0 to the first face. This permits a convenient arrangement of components and means that the beam has a relatively-rigid cross-sectional shape.
Preferably, the beam has the cross-sectional shape of a trapezium. This is a particularly rigid shape. In addition with the first surface and an upper, parallel, third face being arranged generally horizontally, the third face can form a support for connecting cables or tubes to the scanning head member.
In a preferred embodiment a drive mechanism in the form of a drive belt is located between the encoder device and the second portion of the second face to constitute a particularly compact arrangement.
In preferred embodiments of the present invention the scanning head member of the scanning device has a separate support region incorporating a bushing for sliding on a second guide member of the structural beam, the bushing comprising a portion having a part-spherical surface, which engages and can rotate in a limited manner relative to a corresponding surface of the scanning head member, and a flexible arm extending from the bushing portion and attached to a formation on the scanning head member. It will be appreciated that this constitutes an independent aspect of the present invention.
According to another embodiment, the present invention pertains to a hardcopy apparatus including a structural beam having a first face and a second face. The first face is substantially parallel to a scanning plane, and the second face faces a guide member. The guide member is attached to the structural beam. A scanning head member is moveably mounted on the guide member and is operable to move parallel to the scanning plane. In addition, substantially all of the second face is inclined to the first face.
According to yet another embodiment, the present invention relates to a hardcopy apparatus including a structural beam having a first face and a second face. The first face is substantially parallel to a scanning plane, and the second face faces a guide member. The guide member is attached to the structural beam. A scanning head member is moveably mounted on the guide member and is operable to move parallel to the scanning plane. In addition, the hardcopy apparatus includes a drive mechanism for moving the scanning head member. The drive mechanism includes a drive belt arranged in front of the second face. The hardcopy apparatus further includes an encoder device for determining the position of the scanning head member relative to the structural beam, in which the encoder device is arranged in front of the second portion of the second face and in which at least part of the second face is inclined to the first face.